expanding, help and fertilizers

Ive been doing lawn care for hire since I was ten, but just as a way to earn spending money. Now i'm 20 and am looking to expand big time in the western wisconsin area. I know that I need to start doing fertilizing, pesticides, and herbicide spraying, but haven't a clue what to do. I have to winter to prepare for it, so I do have time on mys side.

Any help in what do to would be great, along with any advice on how to get GOOD clients, commercial clients, etc.. It seems my city is not a overflowing pot of money when it comes to the ease of getting clients, I have ran telephone book ads and newspaper ads for years and have not gotten hardly any business.